Elevated showers and potentially a few thunderstorms may move northwards into Channel Isles and southern and southeastern England from Wednesday evening into Thursday morning. It should be stressed that most of the day will remain dry across southern Britain and this risk if generally from 18z onwards.

A marginally unstable mid-level airmass will be characterised by MUCAPE values of around 200 J/kg overnight across the Channel and near southern England, along with Boyden values of 95-96. Lightning is considered a low risk with this initial wave of mid-level instability, but further potential will persist on Thursday through the weekend.